1. intelligent, judicious, wise, equitable. Reasonable,rational refer to the faculty of reasoning. Rational can refer to the reasoning faculty itself or to something derived from that faculty: rational powers; a rational analysis. It can also mean sane or sensible: She was no longer rational; a rational plan.Reasonable most often means sensible: A reasonable supposition is one which appeals to our common sense.2. equitable, fair, just. See moderate.

What the majority of people consider to be 'reasonable' is that about which there is agreement, if not among all, at least among a substantial number of people; 'reasonable' for most people, has nothing to do with reason, but with consensus. [Erich Fromm, "The Heart of Man," 1968]

Meaning "moderate in price" is recorded from 1660s. Related: Reasonably.